Traffic signs are essential to safe driving. Traffic signs visually represent instructions to drivers and pedestrians. Some instructions may include orders, such as a speed limit, or an instruction to stop. Other instructions may include a warning of dangers ahead, such as dangerous curves, construction work, etc.
Traffic signs may be permanent or changing. A stop sign at a crossroads is a permanent sign. A traffic light, on the other hand, is a changing sign, which displays different instructions at different times: red light instructing drivers to stop, yellow light instructing drivers to yield, green light instructing drivers to go, green arrow lights instructing drivers to go in directions shown by the arrow.
It is of paramount importance for drivers to pay attention to traffic signs, for their own safety and for the safety of other drivers and pedestrians around them. Drivers, however, may be sometimes distracted and may not pay attention to traffic signs.
Self-driving vehicles include sensor systems and algorithms to enable onboard computers to drive cars. Among their many systems, self-driving vehicles include visual sensors (e.g., cameras) and complex image processing algorithms to identify traffic signs, in order to control the car's behavior according to the instructions of the traffic signs.